David Cameron moves Andrew Mitchell as reshuffle begins
David Cameron has moved Andrew Mitchell from International Development Secretary to government chief whip, as he starts his first major reshuffle.
The prime minister is also expected to bring Liberal Democrat David Laws back as speculation mounts over the future of several cabinet members.
But the chancellor, home secretary and foreign secretary are all expected to keep their jobs.
The reshuffle comes amid growing Tory concern over the coalition.
Mr Cameron is finalising the details of the reshuffle, the first major shake-up since the Conservative-Liberal Democrat government came to power in 2010.
Tuesday morning's cabinet meeting has been cancelled to allow the prime minister to deal with the reshuffle.
Mr Mitchell, a former soldier, will replace Patrick McLoughlin as government chief whip, whose main role is to get Conservative MPs to vote in favour of coalition legislation. Mr Mc Loughlin's new role has not been revealed.
Mr Cameron said: "Andrew has done a superb job as Britain's development secretary. He has made British development policy transparent, focused and highly effective.
"His energy and passionate commitment have placed Britain at the forefront of international efforts to improve the lives of millions of the world's poorest people. He has made a real difference.
"As chief whip, Andrew will ensure strong support for our radical legislative programme, by working hard to win the argument in the Commons as well as playing a big role in the No 10 team.
"He will be invaluable as the government embarks on the next, vital phase of its mission to restore our economy to growth and reform our public services."
Any cabinet changes are thought unlikely to affect Chancellor George Osborne, Home Secretary Theresa May and Foreign Secretary William Hague.
However, most other ministers could not be "sure about their futures", BBC political editor Nick Robinson said.
There has been speculation about possible moves for Justice Secretary Ken Clarke, Health Secretary Andrew Lansley, Culture Secretary Jeremy Hunt, Conservative chairman Baroness Warsi and Welsh Secretary Cheryl Gillan.
Leaving the Houses of Parliament, Mr Clarke was asked if he had any details of the reshuffle, replying: "The only news is I'm off to have a curry."
Former Liberal Democrat cabinet minister David Laws is expected to return to the government in some capacity - two years after resigning as chief secretary to the Treasury after admitting he claimed expenses to pay his partner's rent.
Lady Warsi has appealed to David Cameron to allow her to keep her post in any reshuffle.
She said she would like to "stay doing what I'm doing" and argued that as a northern, female Muslim she could help the party attract a new generation of voters.
Housing minister Grant Shapps, employment minister Chris Grayling and minister for disabled people Maria Miller are among Conservatives tipped for promotion.
The reshuffle comes after several Conservative MPs accused the coalition of not doing enough to promote economic growth.
Former shadow home secretary David Davis has urged ministers to deliver "shock therapy", with more tax and spending cuts pushed through.
The government has said it will underwrite up to £50bn of private sector building projects which need finance.
The Treasury said it would build on on a scheme launched in July, allowing £40bn of construction projects by using the government's low interest rates to underwrite them.
Ministers are also expected to set out plans to underwrite construction of up to £10bn worth of new homes, including guaranteeing the debt of housing associations and private sector developers.
In addition, the government will legislate to speed up planning decisions and encourage development of Green Belt land, if certain conditions are met.